Induction pump



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INDUCTION PUMP Filed Jan. 19, 1968 10 Sheets-Sheet 10 Q s KL II7VP/7f0l': E RusT New GR BY mmAQlqL- United States Patent 3,459,132 INDUCTION PUMP Ernst Meyer, Roderstrasse 12, Olfenbaeh am Main, Germany Filed Jan. 19, 1968, Ser. No. 699,067 Claims priority, application Germany, Jan. 28, 1967, M 72,579 Int. Cl. F04b 17/04 US. Cl. 103-53 11 Claims ABSTRACT OF THE DISCLOSURE There is disclosed an induction pump for pumping a large volume of a flowable medium within a wide range of pressure and temperature. The pump comprises an open-ended cylinder one end portion of which constitutes a suction conduit and the other a pressure conduit. A magnetizable hollow plunger is guided with clearance within the cylinder and is also guided with clearance upon an open-ended pipe extending into the plunger from either the suction conduit or the pressure conduit secured to the respective conduit. Due to such mounting and guidance the cylinder and the plunger can compensate within a wide range for deformation thereof as may be caused by temperature changes, insufiicient alignment of the components of the pump during assembly thereof, etc. The pumping action is obtained by reciprocating the plunger within the cylinder by variations of a magnetic field inductively applied to the plunger.

The present invention relates to an induction pump, that is, to a pump in which the pumping action is obtained by the stroke of a reciprocating plunger activated by a suitably controlled magnetic field rather than by the action of a rotor of an electric motor. More particularly, the invention relates to an induction pump in which the suction conduit and the pressure conduit are disposed in alignment with the direction of the stroke of the plunger.

One of the problems with induction pumps of the general kind above referred to is that in such pumps the stroke length of the plunger is dependent on the vacuum and pressure conditions prevailing during the operation of the pump. There is a tendency of the plunger to wander out of the saturated magnetic field in response to certain changes in the operational suction and pressure conditions and to move into a position in which a condition of equilibrium exists between the magnetic attraction and the pressure acting upon the plunger. Obviously, when such condition of equilibrium occurs the pumping action ceases. As a result, induction pumps as generally known with axially aligned suction and pressure conduits, while capable of pumping a substantial volume of a flowable medium such as oil, are suitable only for pumping at a low pressure.

My prior Patent 3,348,489 issued Oct. 24, 1967 discloses an induction pump which comprises an open-ended cylinder one end portion of which constitutes a suction conduit and the other a pressure conduit. A tubular plunger is slidable in the mid-portion, of the cylinder and defines an open passageway extending between the two end faces of the plunger. The plunger has a tubular extension of lesser diameter than the outer diameter of the plunger on each of its end faces in alignment with the hollow interior of the plunger. These extensions protrude into the end portions of the cylinder and are slidably guided therein. The plunger is made of magnetizable material and the mid-portion of the cylinder is surrounded by a coil. The magnetic field generated by this coil when excited is controlled to impart to the plunger the required reciprocating movements within the cylinder.

Induction pumps according to my prior patent are capable of pumping a large volume of flowing medium at a high pressure but they are adversely affected by high temperatures of the medium to be pumped and the resulting heating of the cylinder and the coil surrounding the same.

It is an object of the present invention to provide a novel and improved pump of the general kind above referred to which is not only capable of pumping a large volume of a flowable medium within a wide pressure range but also of reliably operating within a wide temperature range.

A more specific object of the invention is to provide a novel and improved induction pump in which pulses of a magnetic field used for reciprocating the plunger are applied to the pump by means of a ferrous yoke encompassing the cylinder while the coil for generating a pulsating magnetic field is located spaced apart from the cylinder. Such an arrangement has the advantage that there is a highly eflicient magnetic coaction between the magnetic field and the plunger but that transfer of heat from the pump to the coil is greatly reduced.

Another more specific object of the invention is to provide a novel and improved induction pump in which the pulses applied to the plunger to cause reciprocation thereof are D-C pulses and the plunger is pre-magnetized either by a suitably disposed permanent magnet, or by a D-C energized coil mounted on the same yoke as the coil or coils used for generating the DC pulses causing reciprocation of the plunger or on a separate yoke. It has been found that such pre-magnetization of the plunger results in a significantly increased efficiency of the pump.

It is also an object of the invention to provide a novel and improved induction pump which includes heating means for pro-heating the medium before it is Subjected to the pumping action. As it is well known, media having a high viscosity such as heavy oils when cold, cannot be efficiently pumped with induction pumps as heretofore known. The provision of the heating means permits a lowering of the viscosity of the medium to a value at which the pump is capable of efficiently operating.

The aforepointed out objects, features and advantages and other objects, features and advantages which will be more fully pointed out hereinafter, are obtained by guiding the plunger not only with clearance in the cylinder but also floatingly on a pipe extending either from the suction end or the pressure end of the cylinder secured thereto rather than by guiding the plunger by means of extensions at the ends of the plunger and protruding with clearance into the suction end and the pressure end of the cylinder as is shown in my aforesaid prior patent.

In the accompanying drawing, several embodiments of the invention are shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a lengthwise sectional view of an induction pump having a dual electromagnetic driving system;

FIG. 2 is a lengthwise sectional view of a modification of the induction pump having a single electromagnetic driving system;

FIG. 3 is a lengthwise sectional view of a pump similar to FIG. 1, but modified with respect to the arrangement of the plunger and its guidance;

FIG. 4 is a lengthwise sectional view of a pump similar to FIG. 2, but modified with respect to the arrangement of the plunger and its guidance;

FIGS. 5 to 8 inclusive are diagrammatic views of several modifications of the electromagnetic driving system of the pump;

FIG. 9 is a diagrammatic view of the cylinder of the pump equipped with heating means for heating the medium to be pumped;

FIG. 10 shows a modification of the arrangement of the heating means shown in FIG. 9;

FIG. 11 is a diagrammatic view of a further modification of the arrangement of the heating means;

FIG. 12 is a lengthwise sectional view of a prior art induction pump with a dual electromagnetic driving system; and

FIG. 13 is a lengthwise sectional view of a prior art induction pump with a single electromagnetic driving systern.

Referring first to FIGS. 12 and 13, the pump as exemplified in these figures comprises a hollow open-ended plunger E from both ends of which extend pipes G1 and G2. The outer diameter of these extensions is less than the outer diameter of plunger E. Extension G2 protrudes with play into a suction conduit A1 fitted into cylinder A of the pump. Similarly, extension G1 extends with play into a pressure conduit A2 fitted in cylinder A. The facing surfaces of A1, G2 and A2, G1, act as guide surfaces. Obviously, the smaller the clearances between the plunger extensions and the conduits are, the less pumped medium can flow back from the pressure side L2 to the suction side L1, thus correspondingly increasing the efiiciency of the pump.

In actual practice, the distance between suction conduit A1 and pressure conduit A2 is bound to be quite large. As a result, the extension pipes G1 and G2 and also the plunger E have to be quite long. Practical experience shows that it is very difiicult to mount the coacting long parts A1, G2, E, G1 and A2 in substantially perfect alignment. To prevent jamming of pipe G2 in conduit A1 or of pipe G1 in conduit A2 the clearances between pipe G2 and conduit A1 and between pipe G1 and conduit A2 must be rather considerable. Moreover, if there is a possibility of a deformation of cylinder A due to changes of temperature or of stresses in the material from which the respective parts are made, a still larger clearance must be used in practice. As is apparent from the previous explanation, the efficiency of the pump and the extent of the clearances between the conduits and the plunger extensions are inversely proportional. In other words, large clearances cause poor efliciency of the pump.

As stated before, the object of the present invention is to provide an induction pump which assures reliable and smooth reciprocating movements of the plunger even if the temperature of the medium to be pumped varies Within a wide range and deformations of the cylinder and of the suction and pressure conduits may occur due to changes in temperature, relief of stresses within the material, inaccurate assembly, etc.

The object of the invention is accomplished by eliminating the hollow extension pipes G1 and G2 secured to plunger E by means of which the plunger is slidingly or floatingly guided in suction pipes A1 and A2, as is shown in FIGS. 12 and 13. Instead, the suction conduit A1 or the pressure conduit A2 has secured thereto a pipe G2 which protrudes with clearance into the open end of plunger E thereby slidably or floatingly guiding the plunger on the pipe, the other end of the plunger being closed.

FIGS. 1 to 4 inclusive show diagrammatically induction pumps constructed in accordance with the invention.

Referring first to FIG. 2 more in detail, this figure shows an induction pump equipped with a single electromagnetic driving system including a coil D encompassing cylinder A. This coil when excited generates a magnetic field traversing hollow plunger E made of magnetizable material as previously stated. Suction conduit A1 which includes a conventional one-way valve B such as a ball valve, has secured thereto at C a pipe G2 on which the plunger is floatingly guided. The outer diameter of the plunger is less than the inner diameter of cylinder A. Accordingly, the plunger will not come into engagement with the inner wall of the cylinder even if the center axis of the plunger should be out of alignment with the axis of the cylinder to a rather considerable extent.

The function of the induction pump according to FIG. 2 is as follows:

The plunger E is maintained by suitable and conventional means such as a permanent magnet or one or several pressure or tension springs F1 and F2 in a predetermined lengthwise position in reference to the electromagnetic system D. By feeding a direct current pulse to the coil of the electromagnetic system D the plunger is displaced in the direction of the arrow due to the magnetic attraction experienced by it. A valve H which is fitted in the closed end of the plunger and should also be visualized as a conventional one-way valve such as a ball valve, is set to remain closed when the plunger moves in the direction of the arrow. As a result, any medium present in cylinder A on the upstream side of the plunger or already in space L2 of pressure conduit A2 is pressed in the direction of the arrow. Simultaneously, plunger E sucks fresh medium into the space L1 of suction conduit A1 via valve B now forced open due to the enlargement of the space K within the plunger. The fresh medium will fiow from the space L1 through pipe G2 into space K. Upon decay of the pulse supplied by the electromagnetic system D a pull in the direction of the arrow is no longer applied to the plunger so that the same returns into its initial position or even beyond the same by the action of the springs. Valve B is closed during such return movement of the plunger. The fresh medium which thus has been forced into space K is pressed through valve H now open into the interior of cylinder A on the upstream side thereof.

If desired, the electromagnetic system D of cylinder A can also be so disposed that a magnetization of the plunger results in a displacement thereof in the direction opposite to that indicated by the arrow.

Turning now to FIG. 1, the dual electromagnetic driving system according to this figure comprises coils D1 and D2, which are alternately fed with a current pulse so that plunger E is pulled by the field of one coil in one direction and by the field of the second coil in the other direction.

The function of the pump of FIG. 1 is otherwise the same as previously described.

FIGS. 3 and 4 show plunger arrangements in which pipe G2 is not secured to suction conduit A1 as is shown in FIGS. 1 and 2 but to pressure conduit A2. Valve H is now located not at the forward end of plunger E but at the rear end thereof.

Functionally, the pumps of FIGS. 3 and 4 operate in the same manner as has been described in connection with FIGS. 1 and 2.

As is shown in FIGS. 1 to 4 inclusive, the center axis of cylinder A is axially aligned with the coils of electro magnetic system D and D1, D2. When in a pump arrangement of this kind the medium flowing through cylinder A is at a high temperature there is a danger that the coils D and D1, D2 of the electromagnetic systems are heated to a dangerously high temperature. If now the distance between the coils and the cylinder is increased, with or without the interposition of thermal insulation material, for the purpose of reducing transfer of heat from the cylinder to the coils, such increase in spacing would correspondingly increase the magnetic spacing between the coils and plunger B. As is evident, such increase in the spacing between the coils and the plunger will cause a corresponding reduction in the effective force of the magnetic field and thus a significant decrease of the magnetic pull exerted upon the plunger.

In order to protect the coils from the heat of the cylinder without reducing the efficiency of the magnetic field, FIGS. 5 to 8 provide structures in which the temperaturesensitive coils are thermally separated from the cylinder by placing the coils in positions in which there is a substantial spatial distance between the coils and the heat radiating cylinder.

As is shown in FIGS. 5 to 8, coils D1 and D2 are magnetically closely coupled with cylinder A but thermally very loosely. More specifically, the cylinder and thus the plunger therein are surrounded by branches M1 and M3 of a ferrous yoke M1 so that there is a close magnetic coupling but the coils D1 and D2 are placed at a considerable distance from the cylinder so that they will not be heated to dangerous temperatures.

Tests have shown that induction pumps driven by magnetic pulses generated by a pulsating direct current show a significant increase in efficiency when a uniformly directed premagnetization is applied to the plunger.

As is shown in FIGS. 5 and 6, a coil D3 continuously energized by direct current is mounted on a branch M3 of yoke M. If desired, such coil D3 or several such coils excited always in the same direction with direct current can also be mounted on yoke branches M, M1, and M3 or on all three branches side-by-side with induction coils D1 and D2, or encompassing the same.

Instead of coil D3 energized with direct current as is shown in FIGS. 5 and 6, permanent magnets P such as shown in FIGS. 7 and 8 can also be used. Such permanent magnets can also be interposed in the structures shown in FIGS. 5 and 6 in the yoke branches M, M1, M2 and M3.

The output of an induction pump depends upon its stroke. If the power supply fed to a pump is increased, the stroke and with it the output of the pump will increase only until the magnetic field reaches saturation. Driving a pump at or close to its saturation point entails the use of an uneconomical amount of energy. Hence, induction pumps are usually operated at about of magnetic saturation.

Assuming now that the power feed to a pump is maintained constant, an induction pump changes its stroke and tained constant, an induction pump changes its stroke and thus also its output when the viscosity of the medium to be pumped changes. Such change in the output is approximately proportional to the change in viscosity.

Heretofore media having a high viscosity such as cold heavy oils could be pumped by induction pumps only with a very low efliciency. In order to obtain a satisfactory efliciency of induction pumps when media having a high viscosity such as heavy oils are to be pumped, the invention provides according to FIGS. 9, 10 and 11 a heating means R at or near the suction side of the pump for the purpose of heating the medium and thus lowering this viscosity before the medium enters the pump proper.

According to FIG. 9, heating means R which may be visualized as a conventional heating element, may be mounted directly on cylinder A near the coil of the electromagnetic system D1 if the temperature to which the medium is to be heated is comparatively low.

If there is a danger of a too large transfer of heat from heating means R to the coil the heating means are preferably mounted on a separate pipe or duct A5 as is shown in FIGS. 10 and 11.

As is evident, such mounting of the heating means on a separate pipe or duct permits placement of the heating means in any desired position.

The provision of a heating means of an induction pump for the purpose of changing the viscosity of the medium to be pumped can be advantageously used also in connection with the pumps shown in FIGS. 5 to 8. In the pump structures according to these figures there is a comparatively large distance between the pump cylinder and the electromagnetic driving systems so that a large transfer of heat from the heated medium to the coils is avoided even if the medium is heated to a high temperature.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention, it will be understood by those skilled in the art, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. An induction pump for pumping a fiowable medium, said pump comprising in combination:

an open-ended cylinder, one end portion of the cylinder constituting a suction conduit and the other a pressure conduit;

induction coil means energizable by direct current pulses disposed outside said cylinder for generating a magnetic field traversing the cylinder;

a magnetizable hollow plunger open at one end and closed at the other end slidable with play within said cylinder intermediate the end portions thereof, the lengthwise position of the plunger in the cylinder being controlled by the state of excitation of the magnetic field generated by said coil means;

a one-way valve means in the closed end of the plunger, said valve means opening upon displacement of the plunger in one direction to permit a flow of medium through the plunger and closing upon displacement of the plunger in the opposite direction;

an open-ended guide pipe extending from either end portion of the cylinder secured thereto into the open end of said plunger for slidably guiding the plunger within the cylinder, the outer diameter of the pipe portion within the plunger being less than the inner diameter of the plunger; and

directional force means in the cylinder biasing said plunger into a predetermined lengthwise position in the cylinder, excitation of the coil means attracting the plunger into another lengthwise position against the action of the force means.

2. The induction pump according to claim 1 wherein said induction coil means comprise an iron yoke having portions encompassing said cylinder, and the windings of said coil means are disposed on branch portions of said yoke spaced apart from the cylinder thereby protecting the coil windings against damage by a high temperature of the cylinder.

3. The induction pump according to claim 2 wherein said yoke has a generally U-shaped configuration, the branches of the yoke encompassing the cylinder being disposed at lengthwise spaced points.

4. The induction pump according to claim 2 wherein the Winding axis of said coil means is parallel to th axis of the cylinder.

5. The induction pump according to claim 2 wherein the winding axis of said coil means is normal to the axis of the cylinder.

6. The induction pump according to claim 1 and comprising magnetic means for generating a permanent magnetic field traversing the cylinder for premagnetizing the plunger therein.

7. The induction pump according to claim 6 wherein said magnet means comprise a further branch of the yoke also encompassing said cylinder, and further coil means encompasslng said further branch and disposed spaced apart from the cylinder.

8. The induction pump according to claim 6 wherein said magnet means comprise a permanent magnet encompassing said cylinder.

9. The induction pump according to claim 1 and comprising heating means for preheating the medium to be pumped.

10. The induction pump according to claim 9 wherein said heating means encompass the cylinder adjacent to suction conduit thereof. a

11. The induction pump according to claim 9 wherein a feed pipe is connected to the suction conduit of the cylinder and said heating means are disposed in heat transferring relationship with said pipe.

References Cited UNITED STATES PATENTS ROBERT M. WALKER, Primary Examiner US. Cl. X.R. 

